Heat-treating strip



C. H. VERWOHLT HEAT-TREATING STRIP Oct. 7, 1952 2 SHEETS-SHEET l Filed June 28 1949 t m o RW wr Nw WH. me C D z NN. Cf# QN mN am E, @www .79%.

Patented Oct.` 7, 1952 UNITED STATES Pari-:NT

4 oFF-ICE 2,613,070 HEAT-TREATING nSTRIP .y clarence ,n.verwohn, st. ciairsviue, ohio application 51m@ as, 1949,?seria-1No. 101,755

This invention relates to vfheat treating istrip, especially metal strip, and has particular advantages Vin the annealing of ferrous metal strip and especiallysilicon steel strip.

Strip `may 'be heat `treated either inA coils or continuously. Continuous -heat treatment involves a large initial investment in equipmentland presents othei` .problems, particularly iin the lannealing of `certain metals such as f sil-icon steel 4which atthe high temperatures to 'which th'eymust lbe Asubjected tend to `deposit accretions 'on the `portions of the f conveyor lin 'the furnace or Jheating `chamber which come fin contact with ithesurface of the strip.

Heat vtreatment of strip lin-coils in the conventional way-With tithe coil 'Faxes vertical, ,us

`uall-y with several coils stacked :atop lone .an-

other-has the `disadvantages that the coils tend tration of heat into its interior. `eat treatment of strip in coils -hasalso 'had the disadvantage that when a special atmosphere is 'used it `does not readily penetrate 4to the interior of-a tightly wound coil. u i

I have devised a method of 'and 1apparatus for heat treating strip `overcoming the disadvantages of the prior methods. I `heat treat strip in coils with the axes `ofthe coils generally 'thorizontal. 'This avoids the unevennessor Ivvaviness attendant` `,upon heat treatment, Aespecial-ly at `relativelyhigh temperatures, o'fistrip in :coils with i the coils disposed with their axes vertical. i 'Indesirably `arrange strip lin coil ".form in la heating chamber with the axis of l the coil -generally Thorlzontal, apply heat 'to the -lcoil and `maintain the strip in` coil form with the axis of the coillgen- `orally horizontal :throughout the @heat treatment.

:thanfthe `inner convolutionsfthey lengthen to a greater extent. 'Ih'usaduring lthe heat treatment lto sag and become uneven or wavy and vthat it `is `diiilcult to obtain uniform heat treatment throughout a coil vbetause of thediiculty of -pene- 'is claims. (c1. .ac3-f2) Aof the coiled .metal `which has heretofore -been the convolutions at `.the "bottom of :the coil :are 4somewhat separated. As the coil rotates `successive portions of the convolutions become thus separated. The result is Ka .continuous opening up fof the =c`oil at the bottom fas it rotates and :a sucking .of the .heatedfatmosphere vwhich surrounds lthe coil .and `an .expelling :of that .atmosphere Sas .the successive portions Aof 'the coil move from-Lthebottom toward lthe top. Thus hot gases are `continuously. .finding their way between the convolutionsof 'theicoilat :the ,bottom .randfrel -ativel-y cool -gases `vvhose heathas ,beenitransferred to `the coil fare .expelled 'nearer :the top. ,Inother Avvordspthe gases `surrounding the .coil :are cirr cultured and reeircuiated through it. rrnuthis way I obtain unprecedented themalfefflciency :for the heat `.treatment of `strip in `coils without :impairiing `the Vuniformity of `the .coil. The coil is main- `tained free from Waves, ibeing. uniform ifrom Vend to end. 1

methodiand .apparatusiare well adapted for fthe heat 'treatment :of lstrip in coils in special l l atmospheres. I deslrablyfprovide a shield device Lwhich Lsubstantia'lly `isolates `the coil from the .surround-ingatmosphere and xmay introduce a .special protective or treating atmosphere within .thes'hielddevice inrintimate contactwith the fcoil. The protective atmosphere may becirculatedfbe- `ing kintroduced into v'the `space within `the rshield ldevice aat oneipoint and YWithdrawn at another,

during rotation-of the :mandrel on which the coil lis-wound. rBecause of the-openingup ofthe con- `vclutions lof :the coil .at the `bottom during -the heat 'treatment fthe -specialatmosphere 'comes into l .intimate contact with all portions of thestrip.

The shield device fis. proportioned to provide rclearance at the periphery ofthe coil so that the lconvolutions yof hthe coil may separate somewhat .at the .bottom .or the coil during the Vheat treat ment..

.The strip ,is desirably wound on ya mandrel which may have a cooling fluid passage .therethrough and means maybe provided for circulating `cooling fluid through .the passage duringlrotation of "the mandrel While a coil of stri-pis vbeing heat treated. The mandrel iis preferably removably'mounted for rotation in the 'heating `cham- 'ber so 'that it may be'bodily removed to `a ylocation `remote from the `heating chamber Where a coil is adapted to 'be `Wound thereon and then transferred tothe heating chamber and `mounted ffor rotationthercin The heating chamber ymay Lhave a removable portion adapted -to be `'removed to providean opening for removal andlreplacement of the mandrel. 'I'he heating :chamflcer:may be lmade'in two halves, laibottom half `landavtop half,

v chamber.

chamber.

3 and the top half may be lifted off when the coil is to be changed. A liquid seal may be provided between the bottom and top halves of the heating chamber. The cooling fluid and protective atmosphere connections may be readily disconnected to permit removal and replacement of the mandrel. Desirably the mandrel is removed to a Winder where a heat treated coil is unwound from it and a new coil to be heat treated is wound onto it. The outer end of the coilmay be fastened in any appropriate way, as, for example, by being welded to the convolution of the coil immediately v inside it. The separation of the convolutions of the coil during the heat treatment occurs as above explained through expansion.

Material may be disposed between the convolutions of the coil as it is being wound on the mandrel to prevent adjacent convolutions from adhering to each other. Any suitable material may be employed, such, for example, as magnesium hydroxide, which may be applied by spray- There is no contact of any portion of the coil with any furnace conveyor mechanism other than the contact of the innermost convolution of the coil with the mandrel. Thus my heat treating method and apparatus are of especial utility in the heat treating of silicon steels and other a present preferred embodiment of the invention and have illustrated a present preferred method of practicing the same in which .Figure 1 is a central vertical cross-sectional View through heat treating apparatus taken on the line I-I of Figure 2; and

Figure 2 is a central vertical cross-sectional view through the heat treating apparatus shown inFigure 1 taken on the line II--II of Figure 1,

Figures 1 and 2 being taken at right angles to each other. c

Referring now more particularly to thedrawings, there is shown a heating chamber designated generally by reference numeral 2 which comprises a stationarily mounted bottom part 3 and a complementary top part 4 which is removable from the bottom part 3 to permit the mandrel Vand coil presently to be described to be removed from and replaced in the heating chamber; The top part l is lifted by an overhead crane or other suitable lifting mechanism when the mandrel is to be removed and is replaced in position on the bottom part 3 when the mandrel is returned to its position in the heating A liquid seal 5 is provided about the heating chamber between the bottom part 3 and the top part 4 to seal the parts to the heating chamber together during operation thereof.

Means are provided for applying heat Within the heating chamber 2. Any suitable heat supplying means may be employed. F01.k purposes of illustration I have shown electric heating elements E mounted on the linside of the heating The heating elements are connected with a source of current and are adapted to generate the desired amount of heat within the heating-chamber. l l

Removably mounted in the heating chamber is a coil receiving mandrel designated generally by reference numeral l. rlChe mandrel comprises a hollow shaft 8 of suitable metal such as steel, either plain or alloy, having mounted thereon refractory sleeves 9 and steel flanges il] carrying a steel cylinder H, which may be of ordinary steel or a high temperature alloy steel and may conveniently be in the form of a casting, on which strip is adapted to be wound. Collars l2 are fastened to the hollow shaft 8 as by set screws to maintain the sleeves 9, flanges it and cylinder Ii in fixed position on the shaft. The cylinder H may be welded or otherwise fastened to the flanges which may in turn be welded or otherwise fastened to the hollow shaft. The space between the Iianges may be filled with refractory material.

Pedestals i3 are provided outside the heating chamber at opposite sides thereof for supporting the mandrel. Asteel insert Hl is welded into each end ofthe hollow shaft 8, the insert itself being hollow as shown. A bearing l5 is disposed about each insert I4 and when the mandrel is in place. is bolted tothe corresponding pedestal I3 on which it rests. The mandrel is sealed to the` heating chamber by sealing means I6 at each' end. When the mandrel is in place in the heating chamber the sealing means is bolted to the heating chamberand the bearings I5 are bolted to the pedestals. When the mandrel is to lbe removed all of thebolts are removed so that .the .sealing means and the bearings are carried along with the mandrel.

A coil of strip is shown at Il wound upon the mandrel. For purposes of illustration the strip may be considered to besilicon steel strip. Surrounding the coil is a shield device I8 preferably of steel and which may be of any suitable construction which isolates the coil from the surrounding atmosphere. The shield device is proportioned to provide clearance at the periphery of the coil so that the convolutions of the coil may separate somewhat at the bottom of the coil as the coil revolves during the heat treatment.

A protective atmosphere may be circulated within the shield device- I8, being introduced through a pipe I9 and removed through a pipe 20. Cooling water.l for vcooling lthe mandrel may be introduced into the hollow shaft at 2l and removed at 22. l

Means are provided for slowly rotating the mandrel when it isv in place. A sprocket 23 is fixedly mounted on the mandrel and is connected throughv a sprocket chain 24 with a driving sprocket 25 on the Hshaft 26 of a gear reducer 2l driven through va coupling 28 by an electric motor 29. The mandrel is Vturned very slowly at a speed of perhaps one revolution per minute.

I shall now `describe how my method may be practiced'. The bolts are removed from the sealing means I6 and the bearings I5, the sprocket chain 24 is removed from vthe sprocket 3 `and the gas connections I9 and 20 and the'water connections 2l and 22 are suitably disconnected by means which may be conventional. After disconnection ofthe gas yconnection i9 lthe sprocket chain 24 may beslid endwise off ofthe mandrel, or it may be removed from the sprocket 25 and carried along with the mandrel. The upper part d of the heating chamber is removed by lifting it upwardly to an out of the way position. The entire mandrel with the coil Il thereon and carrying with it seals, bearings and sprocket is lifted upas by, an overhead crane yand set down on appropriate pedestalsat another location wherel i topl tt A i heelectri "heatinglelements amener--` Y overiecojr., 1 annealedgc'ooli Y Inandrellha *desiredlf protectiveforf treatmg atmos- Lgenerate feat iin the heating chamber to crea-te herein-the ``d` `:si`re"d temperature, generally when silicon steel 'strip :is being g wateris circulated through `the phere is circulated within `the shield `device 'l-B :and thefmandrel'isslowly turned'. rIhe action vof the coilifduring heat treatment has 'been vexplaiin'ed above!` `Its c nvolutions" separate somewhat `at the bottom 'of the Icoil due vto expansion to `freely adrrrit"heat` and` protective atmosphere therebetween *1 and -the heated `gas `is alternately i sucked in when-the convolutions `open up 'at the bottom and expelled when they close near vthe top. Thus thefcoil is e'ejctitely heat `treated 'without `defer#- `mation. When the coil is woundfon the mandrel materialfto prevent the convolutions from adhering Vto eachother may be 'introduced between `the convolutions. For example, the 'striplm'ay Abe sprayedwith magnesium hydroxide paint as it is being wound on-the mandrel. Y i

While I have shown and described a present preferred embodiment 4ofI `the invention and a present preferred method of practicing the same, it is to be distinctlyunderstood 'that theinvention is not limited thereto butmay rloe-otherwise variously embodied and practicedwithin 'the scope of the following claims.

l. A method of heat-treating strip comprising arranging the strip in generally circular coil `:form in,`a heating chamber with the axis of the' coil generally horizontal, applying heat to the coil and whileapplying heat thereto maintaining the entirestripin generally circular coil form and rotatingv the coil about its axis.' 'i

` 2;" A method of heat-treating strip comprising arrangingA the 'strip in generally circular coil form ina heating 'chamberfwith the axis of thecoil generally horizontal, applying a protective atmosphere to the coil, applying heat to the coil and while applying the protective atmosphere and heat maintaining the entire strip in generally circular coil form and rotating the coil about its axis.

3. A method of heat-treating strip comprising winding strip on a mandrel to form a coil, positioning the mandrel with the coil thereon in generally circular form in a heating chamber with the axis of the coil generally horizontal, applying heat to the coil and while applying heat thereto maintaining the entire strip in generally circular coilfcrm and rotating the coil about its axis.

ll. A method of heat treating strip comprisingl arranging'the strip in generally circular coil form in a heating chamber with the axis of the coil generally horizontal, substantially isolating the coil from the surrounding atmosphere, admitting a protective atmosphere into contact with the coil, applying heat to the coil and while applying heat to the coil and while the protective atmosphere is in contact therewith maintaining the entire strip in generally circular coil form y and rotating the coil about its axis.

` 5. A method of heat treating strip comprising arranging the strip in generally circular coll 'frum-fA coirge era-ily horizontal; substantially isolating thecoiliirom 'the surrounding atmosphere, circu tingjarprotective atmosphere in contactwith the icoilglapplying heat-'to fthe'coil and while applying heatftofthe ccil`"an'dcirculating the protective atmospherein contact therewith maintaining the entire strip in generally -circular coil form and rotating the coil about its axis.

1;*'161 A "method of heat treating `strip comprising arranging `the'str'ip `in `generally circular coil form in alfieating chamber with the axis of the coil girznerajljly` horizontal, AAapplying heat to the coil andmaintainingithefcntire strip in generallyciroularfcoilrcrmwiththe ax'isioi` thecoil generally tire Astrip in 'generally Circular coliform and rotating the coil about *itsaxis and during such treatment causing :the convolutions of the coil to'separatesomewhatfat the bottom of `the coil to 're'elyiadmtheat therebetween.

8. frmethod'of heat ltreating `strip comp-rising arramgingi-thje `strip inlgenerally circular coil form in a heating Vchamber with the axis of the coil'fgenerally horizontal, applying a protective atmosphere `"to the coil, applying heat to the coil, whilewapplyingth'e protective atmosphere and heatjmaintaining `the 'entire strip in generally circularacoil form and rotating the coil about its axisand `during such 'treatment causing the convolutions 'ofv the' coil lto separate somewhat at the bottom of the coil to freely `adnrifit heat and protective atmosphere there-between.

`'9.lrrrretl'xod'of heat treating strip comprising `winding `strip on a mandrel toyform a coil with material between the convolutionsv of the coil to prevent 4adjacont*convolutions from adhering .to each4 other, positioning `the mandrel vwith the coil thereon in generally circular form in` a heating chamber with the axis of the coil generally horizontal, applying heatto the coil land while applying fheat thereto maintaining the entire A strip in generally circular coil `form and rotating the coil about its axis.

l0. A method of heat treatingstripcomprising winding strip on a mandrel to form a coil with material between the convolutions of the coil to prevent adjacent convolutions from adhering to each other, positioning the mandrel with the coil thereon in generally circular form in a heating chamber with the axis of the coil generally horizontal, substantially isolating the coil from the surrounding atmosphere, circulating a protective atmosphere in contact with the coil, applying heat to the coil, while applying heat to thecoil and circulating the protective atmosphere in contact therewith maintaining the entire stripinV generally circular coil form and` rotating thecoil about its axis and during such treatment causing the convolutions of the coil to separate somewhat at the bottom of the 4coil to freely admit heat and protective atmosphere therebetween.

11. Apparatus for heat treating strip comprising a heating chamber, acoil receiving mandrel adapted to receive a coil of strip to be heat treated `mounted for rotation about its own axis inthe `.heating chamber and Whose axis is substantially horizontal, a shield device applicable il aereas-engineman the are yof `me ily removed to a location remote from the heating" chamber Where a coil is adapted to be Wound thereon and then to be transferred to theheating chamber'and mounted ,for rotation therein, and means for rotating the mandrel about its own axis with the ycoil thereon While mounted in the heatingr chamber to heattr'eat the strip While maintaining .it in coil form. I

13, Apparatus'for heat treating strip comprisi ing a heating chamber, acoil receivingmandrel adapted to receive a coil oi strip to `be heat treated mounted. for rotation about its ovvnaxis in the heating' chamber and Whose axis is sub' stantially horizontal, a shield device applicable to the mandrel about a Coil disposed thereon to substantially isolate the coil from the-surroundy ing atmosphere, the shield device being proportioned to provide clearance at the peripheryof the coil soV that the convolutions Aof the'coil may separate somewhat at the bottom ofthe coil during the heat treatment, andmeans for rotating the mandrel with a coil and the shield device thereon to heattreat the strip While maintaining it in coil form and substantially isolated from the surrounding atmosphere.

la. Apparatus for heat ltreating strip comprising a heating chamber having a removable portion, a coil receiving mandrel adapted to receive a coil of strip to be heat treated removably mounted for rotation about its own axis inthe heating chamber and whose axisis substantially horizontal, the mandrel being adapted to be bodily removed from the heating chamber throughthe opening provided by removal of the removable portion of the heating chamber to a location remote from the heating chamber where conformtective atmosphere.

means, 'for rotating the mandrel with a coil thereon While mounted in the heating` chamber toheat treat'the strip While maintaining .it in 15, Apparatus for heat treating strip comprising *a` heating chamber, a coil receiving'mandrel adapted to receivel afiially thereof an entire coil of strip to be Aheat*treated-mounted for rotation aboutdts own taxis'l in the heating chamber and Whose axis is substantially horizontal, means' for circulating a protective atmosphere' abouty the coiland means for`rotating the mandrelv with a y coil thereon toheat treatthe strip while maintainingit incoil form. A

16. yApparatusfor heat treating strip comprising a'heating chamber, a, coil receiving mandrel adapted toreceive a coil of strip to be heat treated mounted for rotation about its own axis in the heating chamber and Whose axis is substantially horizontal, a shield device applicable to the mandrel about a coil disposed thereon to substantially isolate the coil from the surroundingatmosphere, means forvcirculating a protective atmosphere' about the vcoil within the shield deviceand mea-ns for rotating the mandrel with a coil and the shield device thereon to heat treat the vstrip while maintaining it in coil form and substantially isolated Yfrom the surroundingatmosphere and in intimate contact with thepro- CLARENCE rr. VERWHLT.

v ,REFERENCES CITED The following v.references are of record in the iile of this patent:

l UNITED STATES PATENTS Number n NameA Date vv188,198 ASimonds Mar. 6, 1877 310,402 lFox ,Jan. 6, 1885 L33,445 Roberts Mar. 18, 1890 734,114 Beker July 21, 1903 1,137,293 Schoneman Apr. 27, 1915 1,630,784 Coe May 31, 1927. 1,957,009 Broemel May 1, 1934 .1,977,214` Steckel Oct. 16, 1934 2,109,204 Wilson Feb. 22, 1938 2,495,167 Horstman et al Jan. 17, 1950 

